Summary ? Core C The aims of the Neuropathology Core are: ? to provide a high-quality, comprehensive and standardized neuropathological service to research groups in the program, ? to provide advice and expertise on neuropathological interpretation to research groups in the ? program, ? to record histopathological findings and assessments in a form that is both accessible to the ? research groups in the program and readily integrated with other data for the purposes of ? comparative analysis, ? to develop the classification of mouse model and human central nervous system (CNS) tumors established in programmatic studies to date. A uniform approach to histological analysis is essential to this research program. High-quality histologic methodologies and expert evaluation of preparations will enable a robust and detailed characterization of human and mouse CNS tumors from across the program. There is scope for a detailed comparative analysis at histological and molecular levels of human and mouse model CNS tumors, both within one histopathological category, e.g. astrocytic versus oligodendroglial tumors among the high-grade gliomas, and across categories, e.g. gliomas versus embryonal tumors, such as the primitive neuroectodermal tumor. Histopathological analysis will be critical across programmatic research studies in order to study the effects of genotype on CNS development, to characterize neoplastic events, to determine molecular cytogenetic alterations at the individual cell level, and to evaluate the effects of therapeutics on neoplasms and normal CNS.